North Korea has conducted a test of its underwater nuclear weapons system as a protest against this week's joint military exercises by South Korea, the United States, and Japan, according to state media KCNA on Friday.
The test of the "Haeil-5-23" system, the name given by North Korea to its nuclear-capable underwater attack drones, was carried out by the defense ministry's think tank in the waters off its east coast, the report said, without specifying a date.
The ministry's spokesperson accused the United States, South Korea, and Japan of "getting frantic" with military exercises, warning of "catastrophic consequences."
The three countries' navies conducted regular drills until Wednesday, alongside the US aircraft carrier Carl Vinson, as part of efforts to enhance their responses to Pyongyang's evolving nuclear and missile threats.
"Our army's underwater nuke-based countering posture is being further rounded off, and its various maritime and underwater responsive actions will continue to deter the hostile military maneuvers of the navies of the US and its allies," the North Korean ministry spokesperson said, according to KCNA.
While North Korean state television has previously aired atmospheric explosion tests, monitored by US and South Korean authorities, the reported underwater weapon has not been independently verified.
South Korea's defense ministry issued a warning against North Korea's recent series of weapons tests, calling for an immediate halt. Japan's foreign minister Yoko Kamikawa declined to comment on the North's latest test but pledged continued efforts to curb its weapons development.
Dubbed "Haeil," meaning tsunami, the new drone system was reportedly first tested in March 2023. State media said it was designed for sneak attacks in enemy waters, intending to destroy naval strike groups and major operational ports by creating a large radioactive wave through an underwater explosion.
The reported underwater test comes shortly after North Korea fired a new intermediate-range, solid-fuel hypersonic missile, condemned by Washington, Seoul, and Tokyo as a serious violation of UN Security Council resolutions. The three allies' nuclear envoys gathered in Seoul, condemning Pyongyang's arms trade with Russia and its increasingly hostile rhetoric, coinciding with North Korea's foreign minister's visit to Moscow and meeting with President Vladimir Putin.